But no action is taken. What could be my problem? Any help is appriciated.

Also I have another problem when get emails via webmail (squirrelmail).
Sometimes after retrieving emails cyrus can not recognize my folders and
just can see Trash, Drafts and Sent folder and the cyrus.sub file in
/var/imap/user/f is dissappeared. I have to create that file by hand,
remove cyrus.seen and then reconstruct the mailbox. It happens for many
of my clients. What can I do to solve the problem?